1. Field of the Invention
This invention relates to a one-way clutch of the single gauge type for use in the transmission or the like of an automobile, an agricultural machine or a construction machine or the like. More particularly, it relates to a one-way clutch in which a block bearing is disposed between cam type sprags in a circumferential direction.
2. Related Background Art
In a one-way clutch of the sprag type according to the prior art, as shown in FIG. 3 of the accompanying drawings, an annular retainer 7 made of a highly rigid material such as a steel plate for retaining, for example, gourd-shaped sprags 3a, a ribbon spring for biasing the sprags in an engagement (meshing) direction, etc. are disposed between an outer race 1 and an inner race 2, and bearings 8 are disposed on the opposite sides thereof and have charge of the radial load during the aligning and idle rotation of the inner and outer races. Also, in a construction shown in FIG. 4 of the accompanying drawings, end bearings 9 are disposed on the opposite sides of the sprags 3a and retainer 7.
As described above, the one-way clutch according to the prior art has the highly rigid retainer comprising a steel plate, bearings, etc. Therefore is heavy despite the modest number of sprags, and it requires substantial axial mounting space. It also suffers from the disadvantage of high cost, and it has been difficult to use such one-way clutch in reduction gears for a vehicle having a strict weight limit or in compact gear reduction gears haveing a strict space limit. Further, there has been the problem that when the mounting width of the one-way clutch is small, the length of the sprag is limited by the bearings on the opposite sides thereof so that the capacity of the one-way clutch is limited.
There has been devised a one-way clutch comprising cam type sprags, a retainer of the single gauge type in which a resilient wire material is formed in a U-shaped zigzag fashion, annular side plates, etc. and constructed compactly (see, for example, Japanese Patent Publication No. 63-31011). The construction is shown in FIGS. 5 to 9 of the accompanying drawings. As shown in FIG. 5, cam type sprags 3, a retainer 25 in which a resilient wire material is formed in a U-shaped zigzag fashion, a garter spring 5, annular side plates 20, etc. are disposed between an outer race 1 and an inner race 2.
FIG. 7 is a front view of the cam type sprag 3, and FIG. 8 is a side view of the sprag 3 of FIG. 7 as it is seen in the direction of arrow F. The sprag 3 has a groove 31 into which the garter spring is inserted, a cam curved surface 32 and an arcuate surface 33. The reference numeral 34 designates the bottom surface of the groove 31. FIG. 9 is a perspective view of the annular side plate 20 fitted to the opposite sides of the sprag. In FIG. 9, the reference numeral 21 denotes outer race sliding pieces frictionally sliding on the outer race, the reference numeral 22 designates inner race sliding pieces frictionally sliding on the inner race, the reference numeral 23 denotes recesses into which the wire retainer 25 is fitted, and the reference numeral 24 designates an annular plate portion.
FIG. 6 shows the cross-section VI--VI of FIG. 5, and in this figure, there is shown a state in which the sprags 3, the retainer 25, the garter spring 5 and the left and right annular side plates 20 are combined together. The reference numeral 26 denotes an axial movement stopping member.
With such a construction, the concentricity of the inner and outer races is maintained by the outer race sliding pieces 21 and inner race sliding pieces 22 bent from the annular plate portion 24 of the annular side plate 20, and the annular side plate 20 has charge of the radial load during idle rotation. Since the axial lengths of the other parts than the sprags are only the thickness of the annular side plate 20 and the diameter of the retainer 25, there can be provided a compact one-way clutch in which the axial space requirement is. However, there is the disadvantage that the number of parts is unavoidably great.
If for example, the number of the sprags is reduced to decrease the number of parts in such a one-way clutch, the guiding property of the spring will become bad because the grooves in the sprags constitute the guide of the garter spring. Thus it will become difficult to keep the entire spring in a circular state and as a result, a sufficient biasing force in a meshing direction acting on the sprags will become unobtainable and there will arise the problem that the durability of the spring is spoiled.
Therefore it has been conceived to improve the retainer of the sprags to thereby provide an annular retainer. FIG. 10 of the accompanying drawings is an axial front view, of a construction having such a retainer and FIG. 11 of the accompanying drawings is a cross-sectional view taken along the line XI--XI of FIG. 10. In these figures, the reference numeral 1 designates an outer race, the reference numeral 2 denotes an inner race, the reference numeral 3 designates cam type sprags (identical to those shown in FIGS. 7 and 8), the reference numeral 5 denotes a garter spring, and the reference numeral 6 designates an annular retainer. The sprags 3 are fitted in windows 63 of the retainer 6. The retainer comprises a cylindrical flange portion 61 and an annular flange portion 62, and the windows are formed in the cylindrical flange portion 61. The garter spring 5 inserted in the grooves of the sprags is guided and held by the cylindrical flange portion 61 of the retainer 6 and therefore, even if the number of the sprags is decreased as shown in FIG. 10, the garter spring is held by the outer peripheral portion of the flange portion 61 and maintains a circular state. Thus, the one-way clutch 10 can secure a reliable meshing state.
However, such a retainer alone cannot sufficiently fulfill the bearing function taking charge of radial load.